An A/D converter for converting an input analog voltage to a digital value is known (for example, see Patent Document 1). The A/D converter disclosed in Patent Document 1 generates a determination signal according to a level of the input analog voltage, performs voltage-shifting based on the determination signal such that the sampled and held analog voltage falls in an input voltage range of the A/D converter, and then converts the voltage-shifted voltage to the digital value. Further, the A/D converter remove a component corresponding to the voltage shift from the digital value thus obtained by the conversion, thereby obtaining the digital value corresponding to the analog voltage.
[Patent Document 1] Japanese Laid-open Patent Publication No. 7-7426